1. Field of the Invention
The present invention pertains to an assembly having flow ports that can be selectively actuated or opened by non-mechanical interference to permit communication of fluids and pressure between a first region and a second region. More particularly, the present invention pertains to a downhole sleeve assembly, beneficially includable within a tubular string or other tool assembly, having ports capable of being selectively opened to permit fluid pressure communication and fluid flow through said ports.
2. Brief Description of the Prior Art
From time to time it is advantageous, while controlling fluid flow and/or pressure in a system having an inside and an outside, to selectively open said system to allow fluid to flow and pressure to equalize between said inside and outside of said system. Although other applications can be envisioned, one such situation in which such selective opening is particularly beneficial is in connection with oil and/or gas wells and, more particularly, the stimulation, completion and production thereof.
Horizontal and/or non-vertical directional wells have become common, particularly as technology for drilling, completing and stimulating such wells in shale formations and/or other low permeability reservoirs has improved. However, even with advances in drilling technology, certain limitations exist that prevent optimization of the completion and stimulation of such horizontal and/or extended reach wells. Notably, although current drilling technology has increased the length that non-vertical or horizontal well sections can be drilled, such drilling technology has generally outpaced the ability to stimulate and produce oil and gas from such extended well sections.
One important factor that limits or restricts recovery from extended reach wells is the number of stimulation stages or points that can be effectively deployed in order to treat or stimulate all portions of such wells. Without a viable means of stimulating substantially the entire length of an extended well, the full potential of such deeper (or longer) wells cannot be realized. Put another way, the full benefits of extended reach wells are typically not realized if such wells cannot be stimulated along substantially their entire length.
Several methods are currently utilized to create an opening in wellbore tubular goods in order to equalize pressure and allow fluids to flow between the inside and the outside of said tubular goods. In most instances, said openings are designed to permit: (1) flow of stimulation (such as, for example, hydraulic fracturing) materials from the inside of wellbore tubular goods to reservoir(s) surrounding the outer surface of such tubular goods, and/or (2) production of fluids from such surrounding reservoir(s) into such wellbore tubular goods.
One existing method of creating such openings in wellbore tubular goods involves the use perforating guns which are lowered to a desired location within a well via wireline or tubing. Such perforating guns, which typically employ directional explosive charges, are remotely triggered in order to perforate the walls of such tubular goods. Unfortunately, there are practical limits to the depths/lengths within a wellbore at which such operations can be performed such as, for example, frictional limitations on the length of wireline or tubing that can be used to convey said perforating guns into a well.
Yet another conventional method of establishing communication between the inside and outside of wellbore tubular goods involves use of continuous or jointed tubing equipped with a specialized cutting device(s). Such a device is lowered into a well to a desired location and sand slurry or other abrasive fluid is pumped to the bottom of the continuous or jointed tubing; the abrasive fluid exits the device and erodes opening(s) in a surrounding wellbore tubular using the abrasive effect of such fluid. However, this method is also limited by the practical length that such continuous or other concentric tubing can be conveyed within a well, primarily due to wall frictional forces generated between such continuous/jointed tubing, and said surrounding wellbore tubular goods.
Another method commonly used for creating such downhole opening(s) in wellbore tubular goods involves the installation of at least one ported sliding sleeve and/or other similar apparatus at desired location(s) down hole (such as, for example, on or as part of a production casing string). When desired, such sleeve(s) can be selectively opened by mechanically manipulating the devices, typically using tools that are conveyed into a well via continuous tubing or wireline, thereby exposing such ports. However, use of such sliding sleeves or other similar devices also suffer from significant operational limitations. As with tubing perforation operations described above, frictional forces also limit the length of wireline or tubing that can be used for purposes of shifting or actuating such downhole sliding sleeves.
Certain other conventional downhole assemblies can be selectively opened using droppable or so-called “pump-down” objects such as, for example, balls or darts. Such conventional assemblies are typically operated by a sequence in which a small ball or dart is first dropped downhole. Said first ball or dart lands on a corresponding seat assembly, thereby blocking a fluid flow bore. Application of fluid pressure to said blocked bore facilitates actuation of said sleeve assembly. Thereafter, a slightly larger ball or dart can be dropped to land on a correspondingly sized seat in order to actuate a different sleeve assembly positioned further up hole.
This process can be repeated (generally moving from the deepest or furthest end of the well toward the surface) with each successive ball or dart having a larger outside diameter than the immediately preceding ball or dart. It is to be observed that the overall number of balls or darts that can be used in this manner is limited by the inside diameter of the surrounding tubular. As such, the total number of selectively actuated sliding sleeve assemblies that can be used is likewise limited.
Certain other devices utilize a consistently-sized droppable object (such as, for example, a plurality of balls all having a uniform outside diameter) to engage and operate a selectively actuated downhole apparatus. However, such devices generally require complex mechanical assemblies to operate. Use of such mechanical assemblies are particularly problematic during cementing and stimulation operations, because cement and stimulation proppant material (such as, for example, “frac sand” used in hydraulic fracturing operations) can invade such mechanical assemblies and negatively affect their operation.
The equalization assembly of the present invention overcomes the limitations of existing methods, permitting wells to be drilled with longer extended sections and to be optimally stimulated for greater production rates.